But what if your problem isn’t dirty water? What if your problem is not enough water?

How to deal with severe droughts?

Everyone seems to be aware of energy issues these days. But we don’t think about water much until we don’t have it. Yet energy and water are intimately connected. We need water to produce energy, and we need energy to get our water.

California could be facing a water shortage sooner than expected. The state is in the midst of the worst drought in 500 years. Reservoirs are facing critical shortages. And with severe weather patterns prevalent everywhere, more frequent and serious droughts are expected in California and other western states.

This can seem like a bleak situation. But there’s something that can help with both the cause and the symptoms. That something has to do with energy. That something is solar power.

Even the staunchest of us solar advocates wouldn’t suggest that solar power is the only solution to our energy problems. We need a mix of renewable energy sources, coupled with energy-efficiency measures. But solar has some important advantages when it comes to water.

How much water do we use to produce energy?

When a drought hits, we hear a lot about taking shorter showers. Then we start hearing that agriculture accounts for a lot more water than home use. What we don’t hear about as much is the biggest use of water in the U.S.: electricity production.

Source: Union of Concerned Scientists

While percentages vary by region, overall, electricity generation uses more water than even agriculture. (California, America’s agriculture leader, is an exception.) Coal-fired and nuclear plants use it for cooling, extraction, and storage. And water also figures prominently in biofuel and natural gas production -- not to mention hydropower.

According to the Union of Concerned Scientists, this means that for each load of hot-water laundry you do using electric appliances, 3 - 10 times more water must be withdrawn at a coal or nuclear plant than you use to wash the clothes. Overall, an average family of four goes through 400 gallons of water in their home per day. If their power comes from coal or nuclear, they’re indirectly using 600 to 1,800 gallons for their energy.

In a state like California, the mix is a bit different. It’s not a big coal and nuke region, so power generation there doesn’t take as much water as agriculture, which is big in the state. But California does use a fair amount of natural gas and hydropower.

Hydroelectric power is obviously going to be an issue in a drought, and it’s now at risk in California The state’s hydroelectric plants depend on rivers and reservoirs that are running extremely low.

Advantages of solar power

However, the same dry weather that’s bad for hydropower is good for solar power.

In spite of shorter winter days, California keeps breaking records for solar generation. Last year, California kept its place as the leading state for installed solar PV, increasing its rooftop solar installation capacity from 1,000 MW to over 2,000 MW. In addition to rooftop solar, California now has 2,926 MW of utility-scale solar in operation, according to the Solar Energy Industries Association.

So can solar take over where hydropower leaves off? Solar PV is definitely a good candidate. The case is a bit murkier when it comes to solar thermal plants, which are getting big in California. The plants use large fields of mirrors to concentrate sunlight and heat water, producing steam that spins power-plant turbines. And they use large amounts of water for cooling.

Technology to the rescue

According to the MIT Technology Review, a technology called dry cooling has started to become more common at solar thermal plants. Though it’s more expensive, researchers are working to improve the technology and reduce its costs. And even though dry cooling still costs more than conventional cooling, it represents only about 5% of the total cost of a solar thermal plant.

Another interesting idea that’s come up recently is using solar power to desalinate water. A startup called WaterFX is pioneering just that. Since California’s Central Valley has a lot of salty water that can’t be used, desalinating it has the advantage of not only increasing the water supply, but also getting it locally. That saves the energy used to pump water to the farmlands. The desalination method being used by WaterFX has another advantage: instead of leaving a lot of harmful waste, it transforms most of the salt waste into something useful, like gypsum or epsom salts. And it’s powered by solar!

And then, of course, there’s good old solar PV. While some water is used to produce the panels, as in all manufacturing processes, once they’re in place, PV panels don’t use water to generate energy. Notice that solar doesn’t even come up in this illustration of projected water needs from the International Energy Agency (IEA):

And solar, whether thermal or PV, confers another very important benefit. It helps reduce the greenhouse gas emissions that have led to the extreme weather we’re now facing around the country -- and around the world.

So it makes sense to move to solar and other renewables, like wind power. Making that change can help preserve our water and help protect our climate. That seems like a high ROI.

Rosana Francescato is the Communications Director for Sunible.com, an online portal that connects installers and homeowners. She also manages Sunible's PV Solar Report. Rosana serves on the board of Women and Cleantech and Sustainability and the steering committee of the Local Clean Energy Alliance. She has hands-on experience installing solar with GRID Alternatives, where she’s been the ...

The graph shows more water is used for thermo electric cooling than for anything else. Surely it doesn't all evaporate. I would believe that it is just as clean after it cools the steam pipes and that most of it is returned to whence it came... But I don't know how much evaporates (or how much for each type of generation, if any).

Good point Todd, In France during the 2003 heatwave, several nuclear power stations were operating under a special dispensation for several weeks after river temperatures exceeded their normal allowed levels!

Were it not for that dispensation, France would probably have had rolling blackouts for weeks just when it needed the most power for air conditioning. In the event that this dispensation had not been given, many more people may have died than the 40,000 or so excess deaths attributed to the heatwave across France.

In regards to the California situation, might it be possible for some coastal power stations to be refitted to allow seawater cooling combined with desalination by the distillation method as they are in Saudi? That way, thermal power stations could be net producers of water rather than users.

I find this article hard to understand. The premise essentially is that since coal plants use a lot of water, we should replace then with solar as it does not need to use water cooling systems but it instead can use a dry cooling method. The issue here is that dry cooling for thermal power plants and other cooling applications has been available for decades and is often applied in the middle east. If you go to refining complexes in the middle east, you will notice reduced amounts of cooling water plumes. So the argument does not really stack up. Another issue of course is that air cooling requires more energy and equipment than wet cooling so that will reduce the efficiency of the operation. If the MIT team think this is a new idea, then they are playing games.

It would be interesting to see calculations based on NET water usage rather than "water withdrawals." This is important because much of our water supplies are used and reused; water is not "used up." Some irrigation water serves to recharge the groundwater; even water that evaporates can come down later as rainfall. An important criterion in this calculation is how much contaminants were added in the use, and how effectively are they removed by natural processes? The cost of cleaning up the "used" water to make it fit for reuse should be factored into water rates for power plants and industrial facilities.

Hi Bob, although your comment is technically correct I think it still misses the most important point. A thermal power plant that uses run-of-river cooling cannot cool and must therefore shut down if the river runs dry or is so low that the maximum allowable temperature of the power plant coolant exceeds the legal limit, i.e. the river biotope is killed by thermal overdose. This is a real challenge during times of drought and especially during a hot dry summer when everyone wants to run the AC at max. The solution for areas where this will be a more persistent problem is to use power generation that does not require cooling water. PV and wind are the main candidates but fuel cells running on methane as feedstock could also be applied.

And of course we can confirm that air cooling is technically possible for traditional thermal power plants. But there is a huge penalty in the form of reduced thermodynamic efficiency when air temps are high. But in any case, the steam cycle must have a certain amount of pure water and some of it is inevitably lost to some evaporation when the system must be opened, and that lost evaporated water must be made up.